1. Field of the Invention
This invention relates generally to a system and method for optically inspecting a machined surface and, more particularly, to a system and method for optically inspecting valve seats in a cylinder head of a vehicle.
2. Description of the Related Art
In manufacturing processes for machined parts, the quality and dimensions of machined surfaces are very important with regards to the end use of the parts. For example, in the automotive industry, it is necessary that valve seats in a cylinder head of a vehicle meet certain manufacturing tolerances. As a result, there is a need to inspect the properties of machined surfaces to assess their quality and to identify and eliminate any defective parts. This is necessary so that a part can be rejected, accepted or further machined based on the results of the inspection.
Existing systems for inspecting machined surfaces sometimes employ a coordinate measuring machine (CMM) to measure the geometry, profile, form and other details of a machined surface. The measurement typically takes place at regular intervals of a manufacturing process. The assessment of other surface defects, such as chipping or tooling marks, is typically done manually by visual inspection. This makes such inspections prone to errors due to the limitations of human visual performance. Further, most existing inspection systems are time-consuming. As a result, the inspection cannot be performed for all machined parts on a manufacturing line because of the added cost.
A need therefore arises for systems that can automate inspection processes and reduce the time required for inspection to make it substantially equal to the tact time of a machining line. The method should, thereby, enable online inspection of all machined parts, instead of a representative sample. Also, such automated systems would eliminate any errors due to human visual performance, thus making the inspection process faster and less prone to error.